1. Field of the Invention
The present invention generally relates to a rotary actuator, such as a hydraulic rotary actuator for use in a suspension of a motor vehicle. Such a hydraulic rotary actuator can essentially have a housing with at least one rib on an inside wall thereof, a motor shaft, disposed at least partially within the housing and having at least one vane on an exterior wall thereof, as well as end caps which seal the ends of the actuator. The housing, motor shaft and end caps define a working area chamber therebetween. The ribs on the inside surface of the cylinder and the vanes on the motor shaft divide the working area into working chambers, which chambers can be alternately supplied with hydraulic medium to relatively rotate the shaft and the housing with respect to one another. Seals are also generally provided inside grooves in the ribs and the vanes, which seals hydraulically separate the work chambers from one another.
2. Background Information
German Patent Application No. 42 29 025.2 discloses one type of rotary actuator in which the manufacturing process is very problematic with regard to the manufacturing of the grooves in the ribs and vanes for the seal units. In this known rotary actuator, the seals used have a width to height ratio that is unfavorable for the inside machining of the cylinder. The grooves for the seal units could only be manufactured to within the required tolerances by means of very costly and complex manufacturing processes, such as spark erosion or slotting. The associated manufacturing expense for this known rotary actuator is therefore unacceptably high for large-scale series production. More economical manufacturing processes, such as broaching with a broaching tool, have failed in the past because the broaching tools broke very quickly due to their small cross-section.
An additional problem is that while multi-part seal units, such as the three part seal unit used by this known actuator, of course work very well, they are also very expensive.